<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>01外间距测试</title>
    <style>
        .fu{
          background-color: rgba(255,255,0,0.3);
          overflow: hidden;
        }
        .fu>div{
          width: 100px;
          height: 100px;
          background-color: rgba(0,255,0,0.6);
          border: 2px solid blue;
        }
        .z1{
            margin-bottom: 30px;
            margin-top: 50px;
        }
        .z2{
            margin-top: 50px;
        }
        .z3{
            margin: 0 auto;
        }
        .z4{
            margin-bottom: 50px;
        }
        span{
            border: 2px solid red;
        }
        .s2{
            margin: 50px 20px;
        }
    </style>
</head>
<body>
<span>span1</span>
<span class="s2">span2</span>
<span>span3</span>
<hr>
<div class="fu">
    <div class="z1">div1</div>
    <div class="z2">div2</div>
    <div class="z3">div3</div>
    <div class="z4">div4</div>
</div>
</body>
</html>